WO2018179528A1

WO2018179528A1 - Light-emitting device

Info

Publication number: WO2018179528A1
Application number: PCT/JP2017/036578
Authority: WO
Inventors: 範明和氣
Original assignee: パイオニア株式会社; 東北パイオニア株式会社
Priority date: 2017-03-27
Filing date: 2017-10-10
Publication date: 2018-10-04

Abstract

According to the present invention, a first light-emitting part (140a) and a second light-emitting part (140b) are provided with organic layers (120a, 120b) between electrodes, respectively. The film thickness between the electrodes of the first light-emitting part (140a) is at least 95% and no more than 105% of the film thickness between the electrodes of the second light-emitting part (140b). In addition, the peak wavelength of the emission spectrum of the first light-emitting part (140a) differs from the peak wavelength of the emission spectrum of the second light-emitting part (140b). The number of layers between the electrodes of the first light-emitting part (140a) is the same as the number of layers between the electrodes of the second light-emitting part (140b).

Description

Light emitting device

The present invention relates to a light emitting device.

In recent years, development of a light emitting device using an organic light emitting layer has been promoted. The light emitting unit of this light emitting device has a structure in which an organic light emitting layer is disposed between two electrodes. Depending on the application of the light emitting device, a plurality of light emitting portions having different emission colors may be formed in one light emitting device.

One method of changing the emission color of the light emitting part is to change the material of the light emitting layer. For example, Patent Document 1 describes that a phosphorescent light emitting material is used as a guest material for a red light emitting portion, and a delayed fluorescent material is used as a guest material for a green light emitting portion.

Patent Document 2 describes that a first light-emitting layer and a second light-emitting layer having different emission colors are stacked, and one of the first light-emitting layer and the second light-emitting layer is caused to emit light by an applied voltage. Yes.

JP 2010-114425 A JP 2012-195244 A

In a light-emitting device using an organic light-emitting layer, when a light-emitting portion is made translucent, a user of the light-emitting device looks at the surroundings through the light-emitting device, and thereby emits light (for example, characters and images) from the light-emitting device. You can try it around.

On the other hand, when the light-emitting device has a plurality of light-emitting portions having different emission colors, the film thickness of each of the light-emitting portions is optimized in accordance with the respective emission color. However, when the light emitting device is in a non-light emitting state, the interference colors may appear to be different from each other in the plurality of light emitting units due to the difference in film thickness of the plurality of light emitting units.

As an example of the problem to be solved by the present invention, in a light emitting device having a plurality of light emitting units having different light emission colors, reducing the difference in interference colors in the plurality of light emitting units is an example.

The invention according to claim 1 includes a first light emitting unit and a second light emitting unit each having an organic layer between electrodes,
The film thickness between the electrodes of the first light emitting part is 95% or more and 105% or less of the film thickness between the electrodes of the second light emitting part,
The peak wavelength of the emission spectrum of the first light emitting unit is a light emitting device different from the peak wavelength of the emission spectrum of the second light emitting unit.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

It is a top view which shows the structure of the light-emitting device which concerns on embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. It is sectional drawing which shows the layer structure of the organic layer which a 1st light emission part has. It is sectional drawing which shows the layer structure of the organic layer which a 2nd light emission part has. It is sectional drawing which shows the modification of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

FIG. 1 is a plan view showing a configuration of a light emitting device 10 according to the embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. The light emitting device 10 is, for example, a segment type display device, a display, or a lighting device, and includes a first light emitting unit 140a and a second light emitting unit 140b. Each of the first light emitting unit 140a and the second light emitting unit 140b includes an organic layer (120a, 120b) between the electrodes. The film thickness between the electrodes of the first light emitting unit 140a is 95% or more and 105% or less of the film thickness between the electrodes of the second light emitting unit 140b. The peak wavelength of the emission spectrum of the first light emitting unit 140a is different from the peak wavelength of the emission spectrum of the second light emitting unit 140b. Hereinafter, the light emitting device 10 will be described in detail.

The first light emitting unit 140 a and the second light emitting unit 140 b are formed using the substrate 100. The light emitting unit 140 is, for example, a bottom emission type, but may be a top emission type or a dual emission type. In the non-light emitting state, the first light emitting unit 140a and the second light emitting unit 140b are translucent. In other words, the first light emitting unit 140 a and the second light emitting unit 140 b transmit at least visible light in a direction perpendicular to the substrate 100.

The substrate 100 is formed of a light-transmitting material such as glass or a light-transmitting resin. The substrate is, for example, a polygon such as a rectangle. The substrate 100 may have flexibility. In the case where the substrate 100 has flexibility, the thickness of the substrate 100 is, for example, not less than 10 μm and not more than 1000 μm. In particular, when the substrate 100 having glass is made flexible, the thickness of the substrate 100 is, for example, 200 μm or less. When the substrate 100 formed of a resin material is flexible, the material of the substrate 100 is, for example, PC (polycarbonate), acrylic, PEN (polyethylene naphthalate), PES (polyethersulfone), PET (polyethylene terephthalate). Talato) and polyimide. In the case where the substrate 100 is formed of a resin material, an inorganic barrier film such as SiN _x or SiON is formed on at least a light emitting surface (preferably both surfaces) of the substrate 100 in order to suppress moisture from passing through the substrate 100. Is preferably formed. The substrate 100 may be a substrate (inorganic organic hybrid substrate) having at least one resin layer and at least one inorganic layer.

In addition, when the light emission part 140 is a top emission type, the board | substrate 100 does not need to have translucency. For example, the substrate 100 may be a metal substrate.

The first light emitting unit 140a is formed on the first surface 100a of the substrate 100, and has the first electrode 110a, the organic layer 120a, and the second electrode 130a in this order from the first surface 100a side. The second light emitting unit 140b is also formed on the first surface 100a of the substrate 100, and has the first electrode 110b, the organic layer 120b, and the second electrode 130b in this order from the first surface 100a side. The

first electrodes

110a and 110b are formed using the same material, and the

second electrodes

130a and 130b are also formed using the same material. The

first electrodes

110a and 110b and the

second electrodes

130a and 130b are all translucent.

The

first electrodes

110a and 110b are formed of a transparent conductive film. This transparent conductive film is a metal-containing material, for example, a metal oxide such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), IWZO (Indium Tungsten Zinc Oxide), or ZnO (Zinc Oxide). The refractive index of the material of the transparent electrode is, for example, 1.5 or more and 2.2 or less. The thickness of the transparent electrode is, for example, 10 nm or more and 500 nm or less. The transparent electrode is formed using, for example, a sputtering method or a vapor deposition method. The transparent electrode may be a carbon nanotube, a conductive organic material such as PEDOT / PSS, or a thin metal electrode (for example, MgAg alloy, Mg, or Ag).

The organic layer 120a is located between the first electrode 110a and the second electrode 130a, and has a plurality of layers. One of the plurality of layers is a light emitting layer 123a described later. Each layer constituting the organic layer 120a is formed by using, for example, a vapor deposition method, but at least a part of the layers may be formed by a coating method.

The organic layer 120b is located between the first electrode 110b and the second electrode 130b, and has a plurality of layers. One of the plurality of layers is a light emitting layer 123b described later. Each layer constituting the organic layer 120b is formed by using, for example, a vapor deposition method, but at least a part of the layers may be formed by a coating method. The light emitting layer 123b of the organic layer 120b contains a light emitting material different from that of the light emitting layer 123a of the organic layer 120a. For this reason, the emission color of the organic layer 120a is different from the emission color of the organic layer 120b. In addition, the peak wavelength of the emission spectrum of the first light emitting unit 140a is different from the peak wavelength of the emission spectrum of the second light emitting unit 140b.

The structure of the organic layer 120a excluding the light emitting layer 123a is preferably the same as the structure of the organic layer 120b excluding the light emitting layer 123b. If it does in this way, except the light emitting layers 123a and 123b, the manufacturing process of the organic layer 120a and the manufacturing process of the organic layer 120b can be made the same. In this case, in the first light emitting unit 140a, the number of layers between the first electrode 110a and the second electrode 130a (that is, the number of layers constituting the organic layer 120a) is the same as that of the second light emitting unit 140b. Of these, the number of layers between the first electrode 110b and the second electrode 130b (that is, the number of layers constituting the organic layer 120b) is the same.

The second electrode 130 is formed of a transparent conductive film, like the

first electrodes

110a and 110b. This transparent conductive film has any one of the structures exemplified as the transparent conductive film constituting the

first electrodes

110a and 110b. For example, the second electrode 130 is formed using a thin metal film such as an MgAg alloy or a metal oxide film such as ITO or IZO.

An insulating film 150 is formed on the

first electrodes

110a and 110b. The insulating film 150 has an opening in each of a region to be the first light emitting unit 140a and a region to be the second light emitting unit 140b. In other words, the insulating film 150 defines the first light emitting part 140a and the second light emitting part 140b. The insulating film 150 is formed using at least one of inorganic materials such as silicon oxide, silicon oxynitride, and silicon nitride. The insulating film 150 is formed using a sputtering method. However, the insulating film 150 may be formed using a photosensitive material such as polyimide resin. The insulating film 150 is formed using a sputtering method or a CVD method.

The light emitting device 10 has a light transmitting part 142. At least a part of the light transmitting unit 142 is, for example, a region between the first light emitting unit 140a and the second light emitting unit 140b, and is a region that does not emit light but transmits light. Note that the light transmitting portion 142 may be provided in another region of the substrate 100 (for example, a region surrounding the first light emitting unit 140a and the second light emitting unit 140b).

Note that the light emitting device 10 may further include a sealing portion (not shown). This sealing part may have a configuration in which, for example, an inorganic film is laminated, or may have a metal layer such as an aluminum foil and an adhesive layer, or an adhesive layer may be formed on the above laminated film. You may have the structure which attached metal foil via.

FIG. 3 is a cross-sectional view showing the layer structure of the organic layer 120a included in the first light emitting unit 140a. The organic layer 120a includes a hole injection layer 121a, a hole transport layer 122a, a light emitting layer 123a, an electron transport layer 124a, and an electron injection layer 125a in this order from the first electrode 110a side. The organic layer 120a may further include other layers. Among these, for example, the hole injection layer 121a may be formed using a coating method such as an inkjet method.

The light emitting layer 123a includes a first host material and a first guest material. The first host material is, for example, CBP, and the first guest material is, for example, Ir (piq) ₃ .

FIG. 4 is a cross-sectional view showing the layer structure of the organic layer 120b included in the second light emitting unit 140b. The organic layer 120b includes a hole injection layer 121b, a hole transport layer 122b, a light emitting layer 123b, an electron transport layer 124b, and an electron injection layer 125b in this order from the first electrode 110b side. Among these, the hole injection layer 121b is the same layer as the hole injection layer 121a, the hole transport layer 122b is the same layer as the hole transport layer 122a, and the electron transport layer 124b is the same layer as the electron transport layer 124a. The electron injection layer 125b is the same layer as the electron injection layer 125a.

Therefore, the hole injection layer 121b can be formed in the same process as the hole injection layer 121a. The hole transport layer 122b can be formed in the same process as the hole transport layer 122a. The electron transport layer 124b can be formed in the same process as the electron transport layer 124a. The electron injection layer 125b can be formed in the same process as the electron injection layer 125a.

In addition, at least one of the hole injection layer 121b, the hole transport layer 122b, the electron transport layer 124b, and the electron injection layer 125b is between the first light emitting unit 140a and the second light emitting unit 140b in the insulating film 150. It may also be formed on the portion that is positioned (that is, the translucent portion 142). In this case, as shown in FIG. 5, at least one layer of the organic layer 120 b is connected to the organic layer 120 a through the insulating film 150.

The light emitting layer 123b includes the same first host material as the light emitting layer 123a and a second guest material different from the light emitting layer 123a. By doing in this way, the luminescent color of the organic layer 120a and the luminescent color of the organic layer 120b can be varied only by changing the guest material. The second guest material is, for example, Ir (ppy) ₃ .

The thickness _{t a} of the organic layer 120a is equal to or less than 105% to 95% or more the thickness _{t b} of the organic layer 120b. Therefore, the thickness of the film between the first electrode 110a and the second electrode 130a of the first light emitting unit 140a is equal to the thickness of the film between the first electrode 110b and the second electrode 130b of the second light emitting unit 140b. It is 95% or more and 105% or less. In order to do this, these layers may be formed so that the thickness of the light emitting layer 123a is equal to the thickness of the light emitting layer 123b.

In the present embodiment, the guest material included in the light emitting layer 123a of the first light emitting unit 140a is different from the guest material included in the light emitting layer 123b of the second light emitting unit 140b. For this reason, the light emission color of the 1st light emission part 140a differs from the light emission color of the 2nd light emission part 140b. On the other hand, the thickness _{t a} of the organic layer 120a of the first light emitting portion 140a is equal to or less than 105% to 95% or more the thickness _{t b} of the organic layer 120b of the second light-emitting portion 140b. For this reason, when the first light emitting unit 140a and the second light emitting unit 140b are not emitting light, the difference between the interference color generated in the first light emitting unit 140a and the interference color generated in the second light emitting unit 140b can be reduced.

As mentioned above, although embodiment and the Example were described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

This application claims priority based on Japanese Patent Application No. 2017-060831 filed on Mar. 27, 2017, the entire disclosure of which is incorporated herein.

Claims

Each comprising a first light emitting part and a second light emitting part having an organic layer between the electrodes,
The film thickness between the electrodes of the first light emitting part is 95% or more and 105% or less of the film thickness between the electrodes of the second light emitting part,
The peak wavelength of the emission spectrum of the first light emitting unit is different from the peak wavelength of the emission spectrum of the second light emitting unit.
The light-emitting device according to claim 1.
The number of layers between the electrodes of the first light emitting unit is the same as the number of layers between the electrodes of the second light emitting unit.
The light-emitting device according to claim 1 or 2,
The light emitting layer of the first light emitting unit includes a first host material and a first guest material,
The light emitting layer of the second light emitting unit includes the first host material and a second guest material different from the first guest material.
The light emitting device according to any one of claims 1 to 3,
The layer excluding the light emitting layer in the organic layer of the first light emitting unit is the same as the layer excluding the light emitting layer in the organic layer of the second light emitting unit.
The light emitting device according to any one of claims 1 to 4,
The first light emitting unit and the second light emitting unit are located on the first surface side of the substrate and transmit light in a direction perpendicular to the substrate.